The redshirt sophomore transferred from Alabama this summer.
The Terps open their season Saturday with a road matchup against Northwestern.
Tagovailoa transferred from Alabama in May.
Jackson is one of four starters from last year's team to opt out.
Williams is the top-rated quarterback in the class of 2021.
The quarterback had announced his intent to leave the program in early February.
Lewandowski racked up 2,804 yards and 28 touchdowns in 10 games for Wisconsin-La Crosse last season.
The Terps are left with Josh Jackson and Lance LeGendre as their lone scholarship quarterbacks.
Pigrome played in 11 games last season, making three starts.
The Spartans are looking to become bowl eligible, while the Terps want to finish the season on a high note.